JPH0387355A - Coating of substrate with copper - Google Patents

Abstract

PURPOSE: To improve the fixability of the copper film on a substrate by disposing argon and oxygen introducing ports and depositing pure copper as a conductive film within an argon atmosphere after the formation of a copper oxide film.

CONSTITUTION: The gaseous argon introducing port 21 is added to the apparatus for coating the substrate 1 with copper by coupling a DC powder source to the sputtering cathode 5 in vacuum chambers 15, 15a, depositing sputtered particles on the substrate 1 by electrical cooperative action with a copper target 3 and introducing the gaseous argon to the substrate. The copper oxide film acting as a binder is formed on the substrate 1 by controlling an oxygen quantity via a flow rate control valve 19. The pure copper is deposited as the conductive film thereon within the argon atmosphere after the regulation of the processing chambers 15, 15a. As a result, the fixability of the copper film is improved.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention has a direct current power source coupled to at least one sputter cathode disposed in a vacuum-enabled processing chamber, the cathode electrically connected to a copper A substrate of, for example, an aluminum oxide ceramic plate or a polyimide film is co-acted with a target which can be sputtered and whose sputtered particles are deposited on a substrate, using a device which can introduce argon gas into a vacuum-enabled process chamber. On how to coach with copper.

[Conventional technology]

A section made of an aluminum oxide housing or a synthetic resin as a supporting electrical wiring, so-called printed circuit board, is coated with a bonding agent made of titanium in the first production step, the bonding agent being coated in the second production step. It is known to use copper as a conductive agent by coating it by sputtering.

The copper coating is then covered with a photoresist and etched in a post-photographic process, for example in a bath of hydrofluoric acid.

This conventional method has the disadvantage, on the one hand, that it is time consuming and therefore expensive, and on the other hand it often leaves chemical traces on the product board, which subsequently renders the board or the finished circuit board unusable. There are drawbacks to doing so.

[Problem to be solved by the invention]

The object of the present invention was therefore to find a method of coating electrically conductive coatings for buttons and electrical circuits, which makes it possible to abandon adhesive coatings from titanium.

In addition, the button can be mounted on the board without making conventional or existing equipment or equipment unsuitable for this purpose or without having to make significant or costly modifications or changes to them. The adhesion of the top sputtered copper coating should be significantly improved.

[Means to solve the problem]

According to the present invention, the above problem is solved by providing an inlet for oxygen in addition to the argon inlet, in which case the introduction of oxygen can be controlled via a valve inserted in the inlet pipe, and the amount of oxygen can be controlled by the first
The solution is to form a copper oxide film that acts as an opening fixing agent in the processing step, and then, after adjusting the argon atmosphere, dispense pure copper so that it is deposited as a conductive film.

〔Example〕

The invention has various possibilities of implementation, one of which is schematically shown in more detail in the attached figures. That is, in FIG. 1, the substrate 1 is shown in the form of a plate made of Al2O3, which is thin and
It should be equipped with a conductive copper coating 2. A copper target 3 faces this substrate 1, and is sputtered.

The target 3 is connected to an electrode 5 via an element 4 having a U-shaped cross section, and the electrode rests on a yoke 6 and dies.
This consists of element 4 and permanent magnets γ, 8.
I have entered 9. The poles of the three permanent magnets 7, 8, and 9 are alternately facing the target 3, and the S poles of the outer permanent magnets 7, 90 are the N poles of the central permanent magnet 8, respectively.
An arc-shaped magnetic field is applied to the entire target 4 around the pole and button. This magnetic field densifies the plasma in front of the target 3, so that the plasma has a maximum density where the magnetic field has its arc maximum. Ions in the plasma are accelerated by an electric field constructed based on a DC voltage generated by a DC power supply 10. This DC power supply 10 is coupled to the electrode 5 via its @ pole and two conductive inductances 1112. The electric field stands perpendicular to the surface of the target 3 and accelerates positive ions of the plasma toward the target 3.

This causes more or fewer atoms or particles to be ejected from the target 3, especially from the region 13.14 where the magnetic field is at a maximum. The sputtered atoms or particles move towards the substrate 1, where they are deposited as a thin film 2.

For control of the aforementioned device, a computer can be provided which processes the data and provides control commands. For example, the value of the measured particle pressure in the processing chamber 15.15a can be entered into this computer. On the basis of these and other data, the computer can, for example, control the gas flow via the valves 18, 19 and the gas inlet pipes 22, 23 and adjust the voltage at the cathode 5.

The enclosed computer is in position to control all other variables, such as cathode current and magnetic field strength. Since such computers are well known, their configuration will not be described.

In order to improve the adhesion of the copper coating 2 on the plate-shaped substrate 1, first a very thin adhesive coating is applied to the surface of the substrate 1.

For this purpose, the substrate 1, which is conveyed through the processing chamber 25 in the direction of the arrow F, is exposed to a gas mixture of an argon button and oxygen, the oxygen component from the container 17 being immediately completely used up by the process which is proceeding. so that a pure argon atmosphere then prevails around the substrate 1 in the processing chamber 25 and correspondingly pure copper is sputtered onto the binder film consisting of copper oxide. .

The application of a copper oxide coating to the support or substrate 1 has two particularly important advantages: the pure copper coating 2 on the support 1, on the key carrier, i.e. for example on the substrate 1.
The adhesion of the electronic components (IC1 resistor,
Capacitors, etc.) can be soldered directly to this coating, without the risk that it will come off during or later during mechanical stress (surface-mounted components).

2. This can be applied, for example, to an etching process to construct discontinuous printed conductors.

This process uses strongly corrosive liquids (e.g. hydrofluoric acid).
This is because it is possible to omit processing the processed product in a bath with a high temperature.

The embodiment according to FIG. 2 is a strip coating device, in which two electrodes 30° 31 are connected to the coating chamber 3.
At the same time, copper is sputtered from the substrate 33, 34 while the strip substrate 35 is being wound from an unwinding roll 36 via a coating roll 37 to a winding roll. A gas inlet pipe opens in the area of the cathode 34 , via which oxygen can flow into the area of the cathode 31 from the gas storage container 41 .

Argon is supplied to the storage vessel 42 through the second gas introduction pipe 40.
Flows into the machining interior 32 from there. During the coating process, the electronic control system 45 meters the amount of gas such that only oxidized steel is deposited on the strip-shaped substrate 35 in the area of the first cathode 31 and pure copper in the area of the second cathode 30. urge

For a better understanding of the device according to FIG. 2, it may be further explained that the turbine 30.31 is installed in the block and can be adjusted by a tube 46° 46a or 47,4γ for conducting the cooling liquid.
a, and the nuclear tube simultaneously supplies current to the target or its magnet from a DC power source 10. The electronic controller 45 that controls the solenoid valves 43 and 44 for gas introduction requires a detailed set of parameters, for which purpose (this is not depicted in detail for a better perspective) and a power supply. It is coupled to a button and, for example, a sensor that detects the pressure in the processing chamber.

In this case, what is important for the present invention is that the amounts of oxygen and argon flowing in during the production of the adhesive film are in an appropriate ratio to each other, and that the speed of the passing strip P and sputter particle flow is appropriate. It is something that has been adjusted.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a sputtering apparatus for coating a plate-shaped substrate using one cathode in an embodiment of the present invention, and FIG. 1 is a schematic cross-sectional view of a sputtering device having two cathodes; FIG. 1...Substrate, 5...Cathode, 10...Direct a power supply, 1
5... Processing room, 15a... Processing room, 19... Masu,
20...Oxygen inlet, 21...Argon inlet, 3
o...Cathode,...Cathode, 2...Processing chamber, 3...Target, 4...Target, 5...Substrate, 9...Introduction tube, 0...Introduction tube

Claims (1)

[Claims] 1. It has a direct current power source (10), which power source is coupled to at least one sputter cathode (5; 30, 31) arranged in a vacuum-enabled processing chamber (15, 15a, 32), said cathode is connected to a copper target (3). ; 33, 34), the target can be sputtered and the sputtered particles are deposited on the substrate (1; 35), using a device capable of introducing argon gas into the vacuum-enabled processing chamber. In addition to the argon gas inlet (21, 40), an inlet for oxygen (20) is used to coat the substrate with copper.
, 39), and the oxygen is introduced through the introduction pipe (23, 39).
The amount of oxygen can be controlled via a valve (19, 43) inserted in the substrate (1, 39) during the first processing step to produce a copper oxide film which acts as a bonding agent on the substrate (1, 35) and processing room (15, 15a; 3
A method for coating a substrate with copper, which is characterized in that after adjusting the argon atmosphere in step 2), the amount of pure copper can be deposited as a conductive film.